WebSocket

HTTP naturally looks like:
Client asks → Server responds

But imagine a chat application. The server needs to send a message the moment another user writes, even when the browser hasn't just made a request.

Client and server establish a persistent bidirectional connection. Secure WebSocket (wss://) typically starts with TCP → TLS → an HTTPS request to upgrade to WebSocket. The server replies “101 Switching Protocols”; WebSocket messages then flow over the same encrypted connection. Client ↔ Server Either side can send messages whenever needed.